Lacosamide is an antiepileptic drug that acts on voltage-gated sodium channels and was approved as an antiepileptic by the Food and Drug Administration in 2008. Although the efficacy and safety of lacosamide have been established in many previous trials, some case reports have shown that it may lead to cardiovascular side effects, especially in patients with electrical conduction system disorders. We herein report a case of life-threatening cardiac arrhythmia caused by lacosamide intoxication that was successfully treated with venoarterial extracorporeal membrane oxygenation.